Cooling device for illumination source

ABSTRACT

An exemplary cooling device includes a hollow cylinder and a number of fins. The hollow cylinder has a top end and an opposite bottom end. The fins are evenly distributed on an outer circumferentila surface of the hollow cylinder along radial directions. Each of the fins includes a first portion, a middle portion, and a second portion. A radial width of each fin measured along a direction perpendicular to a center axis of the hollow cylinder gradually decreases along each of the first and second portions toward the middle portion.

BACKGROUND

1. Technical Field

The disclosure relates to cooling devices, and more particularly, to a cooling device for an illumination source such as a light emitting diode (LED).

2. Description of Related Art

Light emitting diodes (LEDs) have been widely used as illumination sources due to their high brightness, long lifespan, and so on. However, an LED generates a great amount of heat during operation. When an LED operates continuously for an extended period of time, the heat generated may build up and diminish the light output efficiency of the LED. This excessive heat may also shorten the lifespan of the LED. Accordingly, proper and timely dissipation of the generated heat is important.

What is needed is to provide a cooling device for an illumination source which can avoid excessive buildup of heat and improve the lifespan of the illumination source.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a cooling device according to a first exemplary embodiment.

FIG. 2 is an isometric view of the cooling device of FIG. 1, but showing the cooling device inverted.

FIG. 3 is an isometric view of a cooling device according to a second exemplary embodiment.

DETAILED DESCRIPTION

Referring to FIG. 1, a cooling device 100 of a first exemplary embodiment is shown. The cooling device 100 is for an illumination source; and includes a hollow cylinder 110, a number of heat fins 120 evenly distributed on an outer circumferential surface of the hollow cylinder 110 along radial directions, and a number of heat pipes 130 mounted on the heat fins 120.

The hollow cylinder 110 includes a top end 112 and an opposite bottom end 114. The hollow cylinder 110 is configured for supporting one or more LEDs on the top end 112 thereof, and is made of thermally conductive material for transmitting (conducting) heat generated by the LEDs to the heat fins 120.

Referring also to FIG. 2, the heat fins 120 are made of good thermally conductive material such as copper, iron, aluminum alloy or the like, and are used to dissipate heat to ambient air. Each of the heat fins 120 includes a first portion 122, an opposite second portion 124, and a middle portion 126 between the first portion 122 and the second portion 124. An end surface of the first portion 122 of each fin 120 and the top end 112 of the hollow cylinder 110 lie in a same plane. The second portion 124 of each fin 120 defines a cutout 124 a, which is located at an inner side of the second portion 124. A top of the cutout 124 a is bounded by a bottom 124 b of the fin 120, with the bottom 124 b being coplanar with the bottom end 114 of the hollow cylinder 110. Thus an inmost top extremity of the cutout 124 a is located at the bottom end 114 of the hollow cylinder 110. The cutouts 124 cooperatively form a receiving space 123 for receiving LEDs therein. A width of each fin 120 measured along a direction perpendicular to a center axis of the hollow cylinder 110 gradually decreases along each of the first and second portions 122, 124 toward the middle portion 126. Such width is hereinafter referred to as a “radial width.” All of the fins 120 cooperatively form a generally hourglass-shaped heat sink around the hollow cylinder 110.

In the illustrated embodiment, the radial width of each fin 120 decreases according to a same nonlinear progression along each of the first and second portions 122, 124 toward the middle portion 126. Thus, the first and second portions 122, 124 each have curved edges. The nonlinear progression can for example be a geometric progression. In another example, the edges of the first and second portions 122, 124 may be arc-shaped. Thereby, each fin 120 has a generally V-shaped outer profile, with the two sides of the V-shape converging to a middle of the V-shape. Thus the fins 120 cooperatively form two converging V-shaped profiles at opposite sides of the cooling device 100 when the cooling device 100 is viewed from a side thereof, with the two converging V-shaped profiles being symmetrical to each other. The converging V-shaped profiles of the fins 120 simplify the fabrication of the fins 120. In addition, the converging V-shaped profiles provide the fins 120 with increased surface area exposed to ambient air, and enhance the efficiency of convection of ambient air in direct contact with the fins 120. Similarly, the converging V-shaped profiles also enhance the forced convection of such ambient air, for example when a fan (not shown) blows such ambient air.

A circular flange 140 is mounted on end surfaces of the second portions 124 of the fins 120, for supporting and fixing in position corresponding ends of the heat pipes 130.

The heat pipes 130 are used as a heat transfer mechanism that can transport large amounts of heat with a very small difference in temperature between a hotter interface and a colder interface. Each of the heat pipes 130 includes an evaporating end 132 and a condensing end 134. The evaporating end 132 of each heat pipe 130 is mounted on the flange 140 and is in contact with the second portions 124 of two corresponding adjacent fins 120. The condensing end 134 of each heat pipe 130 is mounted to top ends of the first portions 122 of the two corresponding adjacent fins 120.

In typical use of the cooling device 100, LEDs are received in the receiving space 123. Heat generated by the LEDs is transferred to the fins 120 through the hollow cylinder 110, and quickly dissipated from the fins 120 to ambient air. One reason for the efficient dissipation is that the converging V-shaped profiles of the fins 120 can reduce the wind resistance of airflow, thereby increasing the circulation of ambient air. In addition, the heat pipes 130 transfer heat from the second portions 124 to the first portions 122, thereby enhancing heat dissipation and cooling the second portions 124. The converging V-shaped profiles of the fins 120 of the so-called sandglass-like cooling device 100 can help cool the LEDs and thereby increase the lifespan of the LEDs.

Referring to FIG. 3, a cooling of a second exemplary embodiment is present shown. The cooling device 200 is similar to the cooling device 100 in most respects. Therefore similar labels in FIGS. 1 and 3 indicate similar parts of the cooling devices 100 and 200. The cooling device 200 includes a hollow cylinder 210, a number of heat fins 220 evenly distributed on an outer circumferential surface of the hollow cylinder 210 along radial directions, a number of heat pipes 230 mounted on the heat fins 220, and a circular flange 240 mounted on bottom ends of the fins 220. The flange 240 is for supporting and fixing in position bottom ends of the heat pipes 230. The difference between the cooling devices 200 and 100 is that the radial width of each fin 220 decreases according to a linear progression along each of a first portion 222 and a second portion 224 to a middle portion 226. That is, both the first and the second portions 222, 224 have straight, oblique edges. In alternative embodiments, the radial width of each fin 220 decreases according to a linear progression along only one of the first portion 222 and the second portion 224 to the middle portion 226.

It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the disclosure or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the disclosure. 

1. A cooling device comprising: a hollow cylinder comprising a top end and an opposite bottom end; and a plurality of fins evenly distributed on an outer circumferential surface of the hollow cylinder along radial directions; each of the fins comprising a first portion, a second portion, and a middle portion between the first and second portions; a radial width of each fin measured along a direction perpendicular to a center axis of the hollow cylinder gradually decreasing along each of the first and second portions toward the middle portion.
 2. The cooling device of claim 1, wherein the radial width of each fin decreases according to a geometric progression along each of the first and second portions toward the middle portion.
 3. The cooling device of claim 1, wherein the radial width of the each fin has at least one of the following characteristics: the radial width decreases according to a linear progression along the first portion toward the middle portion, and the radial width decreases according to a linear progression along the second portion toward the middle portion.
 4. The cooling device of claim 1, wherein the radial width of each fin decreases according to a linear progression along each of the first and second portions toward the middle portion.
 5. The cooling device of claim 1, wherein a bottom inner side of the second portion of each fin defines a cutout, a top of the cutout is bounded by an edge of the fin, the edge of the fin is substantially coplanar with the bottom end of the hollow cylinder, and the cutouts of the fins cooperatively define a receiving space for receiving at least one light emitting diode (LED) therein.
 6. The cooling device of claim 1, further comprising a plurality of heat pipes, each of the heat pipes comprising an evaporating end mounted to the second portions of two corresponding of the fins and an opposite condensing end mounted to the first portions of said two corresponding of the fins.
 7. The cooling device of claim 6, further comprising a circular flange mounted on end surfaces of the second portions of the fins and connected to the evaporating ends of the heat pipes.
 8. A cooling device comprising: a hollow cylinder comprising a top end and an opposite bottom end; and a plurality of fins evenly distributed on an outer circumferential surface of the hollow cylinder along radial directions; each of the fins comprising a first portion, a second portion, and a middle portion between the first and second portions; an outer edge of each of the fins converging from a top end of the first portion and a bottom end of the second portion toward the middle portion where the outer edge is nearest to a center axis of the hollow cylinder.
 9. The cooling device of claim 8, wherein the outer edge of each fin converges from the first and second portions toward the middle portion according to a geometric progression.
 10. The cooling device of claim 8, wherein a radial width of each fin has at least one of the following characteristics: the radial width decreases according to a linear progression from the first portion toward the middle portion, and the radial width decreases according to a linear progression along the second portion toward the middle portion.
 11. The cooling device of claim 8, wherein a radial width of the each fin decreases according to a linear progression along each of the first and second portions toward the middle portion.
 12. The cooling device of claim 8, wherein a bottom inner side the second portion of each fin defines a cutout, a top of the cutout is bounded by an edge of the fin, the edge of the fin is substantially coplanar with the bottom end of the hollow cylinder, and the cutouts of the fins cooperatively define a receiving space for receiving at least one light emitting diode (LED) therein.
 13. The cooling device of claim 8, further comprising a plurality of heat pipes, each of the heat pipes comprising an evaporating end mounted to the second portions of two corresponding of the fins and an opposite condensing end mounted to the first portions of said two corresponding of the fins.
 14. The cooling device of claim 13, further comprising a circular flange mounted on end surfaces of the second portions of the fins and connected to the evaporating ends of the heat pipes.
 15. A cooling device comprising: a hollow cylinder comprising a top end and an opposite bottom end; and a plurality of fins equally angularly distributed on an outer circumferential surface of the hollow cylinder along radial directions; wherein the fins cooperatively define an hourglass-shaped heat sink around the hollow cylinder. 